When the effluent rises it has some velocity, and hence momentum. When it enters the hood it has a tendency to "reflect" and curl downward and potentially escape. If the hood is deep enough (top to bottom) and the hood fan flow is high enough (cfm) the curling effluent will remain captured and will be exhausted. The barrel design in the picture looks to me (without examining one) like it has adequate depth. W.r.t. ya think's question a few messages up: First I would say that the change from vertical to horizontal should be as large a radius curve as you can fit to minimize pressure loss (as well as noise). The effluent momentum (which is a vector) is being changed in direction. This is akin to stopping it and starting it up again. If it can slide along a curve, the momentum loss is significantly less. There is one commercial ducting source I came across once that uses 90-degree transitions, but embeds a curved shape within the duct to improve the flow. I find it hard to answer the question of what questions to ask. Usually, the answers aren't available. Ideally, one would want to know the fan curve (flow vs. static pressure) and try to estimate all the pressure losses (including the pressure one might pull the house down to with or without make-up air) to see what the real maximum flow rate will be. This can then be compared against estimates of effluent generation rate calculated from the reference below. The power used might be adjusted to represent your cooking style, as rarely would one have all burners on maximum and cooking at the highest pan temperature. One thing is certain, flow rate in the hood has to at least equal the flow rate from all the active burners and pans, and arguably should be higher due to imperfect effluent collection. Implied above is that the hood manufacturer can supply pressure loss of the filters vs. flow rate, as well as that of the hood transitions. Getting that data, even if it were ever measured, would be unlikely, me thinks. I suggest that various hoods be "audited" in showrooms to gain a feel for their noisiness versus their designs. The reference worth reading, even if one doesn't intend to use it for calculations, is "Thermal plumes of kitchen appliances: part 2 cooking mode," by Risto, Hannu, and Pekka. (I've found it on-line whenever I've looked for it. Part 1 is also interesting.) If you do use it for calculations, please note the following apparent errors in their Equation 1: The constant should be 0.05 not 5. The units of phi should be kW, not W. (these corrections make their tables consistent with the equation) You will need a scientific calculator or counterpart software to do the exponents (unless you are very old school and know how to do logarithms). You will also need to convert BTU to kW and cubic meters per second to cubic feet per minute. This is left as an exercise for the student. [insert sociopathic laugh here] kas

Despite being a fan (sorry again...) of remote blowers, I still don't think I'd chuck it all for one unless you are truly kitchen and noise obsessed. As I said on the other thread, 95% of blowers have got to be internal (no reference for that, just an educated guess) and most folks are fine with them. No question at max airflow, the internal will be somewhat louder, but again remember that most of the time you won't be doing that. I'm pretty noise sensitive and our lake house VAH hood with 600 cfm blower internally is loud enough to annoy me. Thus when I started with a clean sheet of paper at the main house i went with the whole remote inline blower/silencer setup (which has cost me some time, money, and stress as we've hit the usual problems as we install ductwork). I think it's optimal but not essential (like so much else in this kitchen).

This is just a guess: I think if you meet the specs and requirements of the remote blower, you should be okay. The important thing is that the size of your duct is at least the size specified for the blower. You might want to confirm that with the blower's manufacturer, if they have a customer service 800#. If your duct size is too small (usually expressed in inches diameter), you will not get the full benefit from the blower, in other words, less than the 1000 cfm. BTW, are you sure you really need all that exhaust capacity? It's really a lot, the sort of thing suitable for a lot of heavy sauteing and grilling, cooking for a big crowd on a regular basis. With all that exhaust capacity, you need to plan also for fresh air intake to compensate for the negative air pressure you will be creating. Plan on having to open a window nearby or, if you really want to get fancy, build in an air intake device inside the venting system. I don't know exactly how they do this -- it's the kind of thing usually installed in restaurants. It's easy to go overboard when planning a renovation. You have to sit back and say, what do I really need, and what will please me?

We fully agree that homeowners should do extensive research including the use of Houzz and other social forms But that also should in our opinion includes speaking to licensed professionals in the supporting fields for their project And that is exactly what we did And we did meet with licensed Structural Engineers , Hvac, general contractor, Electricians and plumbers etc. Every one of them as well researched from their licensing to customer reviews/feedback Houzx is a great form to use but again you don’t really know the background of the people you’re speaking with and their opinions are worth noting but should be validated There comes a point in our experience and knowledge that we have to bow out because we are not professionals in this field Anybody who takes offense to our bowing out should not ...we know limits and cannot provide more than we already have. Please start another strand for future questions as we will not be commenting on this any further.